1. Field of the Invention
The present invention relates to a closure device comprising a closure cap fitting over an open end of a cylindrical housing having a longitudinal axis, the cap having a coincident longitudinal axis and including a transverse end wall extending over the open housing end and defining a bore, and a sealing device arranged between the bore and the open end.
2. Description of the Prior Art
Austrian Patent No. 379,069 discloses; a closure device for a cylindrical housing, in particular a blood-sample tube, which closure device is formed by a cap enclosing an open end of the cylindrical housing. Arranged in the cap is a bore, and provided between the latter and an inner space of the housing is a sealing device. Provided in the bore or in a tubular extension adjoining this bore are projecting portions which protrude beyond the surface of the cap and are covered by the sealing device. Depending on the adhesion force between the sealing device and the cylindrical housing, opening of the closure device without the escape of the medicines or body fluids contained in the housing could not always be ensured.
In addition, a plurality of closure devices for cylindrical housings, in particular for keeping medicines or body fluids, have been disclosed in which one-piece or multi-piece caps have been used with sealing devices. Thus, it is known to close the open end of the cylinderical housing with stopper-like sealing devices which are fixed in turn in these enclosing caps, as, for example, according to U.S. Pat. Nos. 4,465,200, 4,205,754 and 4,089,432, European Patent No. 129,029 and published European patent application No. 257,498. A disadvantage in these closure devices is that very high forces have to be applied in the longitudinal direction of the cylindrical housing in order to overcome the adhesion forces between the sealing device and the cylindrical housings so that medicines or body fluids stored in these housings can escape time after time, and thus chemical burns or infections, in particular during the processing of blood infected with AIDS, can occur. It is also a disadvantage in these closure devices that, when the sealing device is pierced through with a needle to remove the contents, unintentional opening of the closure device can occur.